In an air conditioner, an air cleaner, or the like, a centrifugal fan is used to suck, supply, and discharge air in some cases. An impeller that constitutes the centrifugal fan mainly includes: multiple blades arranged annularly around a rotational axis, and a main plate and a shroud arranged opposite to two blade axial ends that are both ends of each of the blades in the direction of the rotational axis.
As such an impeller of a centrifugal fan, there is an impeller formed by conducting ultrasonic welding to weld between main plate-side blade axial ends of blades and a main plate and weld between shroud-side axial ends of the blades and a shroud, as indicated in Japanese Laid-open Patent Publication Nos. 2008-111393 and 2015-86827. With this configuration, main plate-side welded portions are formed between the main plate-blade side axial ends and the main plate, and shroud-side welded portions are formed between the shroud-side blade axial ends and the shroud.